Golf balls generally include a spherical outer surface with a plurality of dimples formed thereon. The dimples on a golf ball improve the aerodynamic characteristics of a golf ball and, therefore, golf ball manufacturers have researched dimple patterns, shape, volume, and cross-section in order to improve the aerodynamic performance of a golf ball. Determining specific dimple arrangements and dimple shapes that result in an aerodynamic advantage requires an understanding of how a golf ball travels through air.
Aerodynamic forces acting on a golf ball are typically resolved into orthogonal components of lift (FL) and drag (FD). Lift is defined as the aerodynamic force component acting perpendicular to the flight path. It results from a difference in pressure that is created by a distortion in the air flow that results from the back spin of the ball. Due to the back spin, the top of the ball moves with the air flow, which delays the separation to a point further aft. Conversely, the bottom of the ball moves against the air flow, moving the separation point forward. This asymmetrical separation creates an arch in the flow pattern, requiring the air over the top of the ball to move faster, and thus have lower pressure than the air underneath the ball.
Drag is defined as the aerodynamic force component acting opposite to the ball flight direction. As the ball travels through the air, the air surrounding the ball has different velocities and, thus, different pressures. The air exerts maximum pressure at the stagnation point on the front of the ball. The air then flows over the sides of the ball and has increased velocity and reduced pressure. The air separates from the surface of the ball, leaving a large turbulent flow area with low pressure, i.e., the wake. The difference between the high pressure in front of the ball and the low pressure behind the ball reduces the ball speed and acts as the primary source of drag.
Lift and drag, among other aerodynamic characteristics of a golf ball, are influenced by the external surface geometry of the ball, which includes the dimples thereon. As such, the dimples on a golf ball play an important role in controlling those parameters.
Recently, a number of golf ball products in the market place have been introduced with golf ball surfaces featuring visually distinct dimple patterns. Golf balls featuring these visually distinct dimple patterns are most prevalent in the premium distance category. Existing examples of such golf balls include, but are not limited to, the Dunlop XXiO XD Aero, the Bridgestone Tourstage PHYZ, and the Saso Kaede. While these golf ball designs possess a unique visual appearance, the dimple patterns utilized on the golf balls, when compared to conventional dimple patterns, are less aerodynamically efficient.
Other unique dimple designs have also been introduced. For example, isodiametrical dimples, such as those disclosed in U.S. Pat. No. 5,377,989, provide for visually distinct dimple shapes. However, due to the nature of the curvatures in forming the isodiametric shape, these dimples limit surface coverage uniformity and packing efficiency when utilized on golf balls. Accordingly, there remains a need for a dimple geometry that provides a visually distinct golf ball surface texture, while providing improved aerodynamic characteristics and maximized packing efficiency.